So I have heard numerous secondary sources explaining the various reasons for the 8 precepts. Is there is an actual sutta that explains the reason for each of the 8 precepts? (besides simply that the arahants of the past all followed them)

"Do not have blind faith, but also no blind criticism" - the 14th Dalai Lama

"At Varanasi, in the Deer Park at Isipatana, the Blessed One has set in motion the unexcelled Wheel of Dhamma that cannot be stopped by brahmins, devas, Maras, Brahmas or anyone in the cosmos." -Dhammacakkappavattana Sutta

"Go forth, monks, for the good of the many, for the happiness of the many, out of compassion for the world, for the welfare, the good and the happiness of gods and men. Let no two of you go in the same direction." - First Khandhaka, Chapter 11, Vinaya.